Engine exhaust manifold endothermic reactor and associated systems and methods

ABSTRACT

Engine exhaust manifold endothermic reactors, and associated systems and methods are disclosed herein. A system in accordance with a particular embodiment of the technology includes an engine having a combustion region and an exhaust passage coupled to the engine to receive exhaust products from the combustion region. The exhaust passage can at least partially enclose a passage interior region. The system can further include a reactor having an external heat transfer surface positioned in the passage interior region, and a reaction zone positioned in a region enclosed by the external heat transfer surface. A hydrogen donor source can be coupled in fluid communication with the reaction zone of the reactor vessel via a donor passage, and a product passage can be coupled to the reaction zone to receive a reaction product from the reaction zone.

TECHNICAL FIELD

The present technology is directed generally to engine exhaust manifold endothermic reactors, and associated systems and methods. Such systems and methods can include endothermic reactors positioned within an exhaust manifold to receive heat for conducting endothermic reactions.

BACKGROUND

Renewable energy sources such as solar, wind, wave, falling water, and biomass-based sources have tremendous potential as significant energy sources, but currently suffer from a variety of problems that prohibit widespread adoption. For example, using renewable energy sources in the production of electricity is dependent on the availability of the sources, which can be intermittent. Solar energy is limited by the sun's availability (i.e., daytime only), wind energy is limited by the variability of wind, falling water energy is limited by droughts, and biomass energy is limited by seasonal variances, among other things. As a result of these and other factors, much of the energy from renewable sources, captured or not captured, tends to be wasted.

The foregoing inefficiencies associated with capturing and saving energy limit the growth of renewable energy sources into viable energy providers for many regions of the world, because they often lead to high costs of producing energy. Thus, the world continues to rely on oil and other fossil fuels as major energy sources because, at least in part, government subsidies and other programs supporting technology developments associated with fossil fuels make it deceptively convenient and seemingly inexpensive to use such fuels. At the same time, the replacement cost for the expended resources, and the costs of environment degradation, health impacts, and other by-products of fossil fuel use are not included in the purchase price of the energy resulting from these fuels.

In light of the foregoing and other drawbacks currently associated with sustainably producing renewable resources, there remains a need for improving the efficiencies and commercial viabilities of producing products and fuels with such resources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic, partially cross-sectional illustration of a reactor system that receives energy from a combustion engine in accordance with an embodiment of the presently disclosed technology.

FIG. 2 is a partially schematic, partially cross-sectional illustration of a reactor system that receives energy from a combustion engine and returns reaction products to the engine in accordance with an embodiment of the presently disclosed technology.

FIG. 3 is a partially schematic, partially cross-sectional illustration of a reactor system that includes a reactor vessel positioned within an exhaust manifold in accordance with another embodiment of the presently disclosed technology.

FIG. 4 is a partially schematic, cross-sectional illustration of a representative reactor vessel suitable for positioning within an exhaust manifold in the manner shown in FIG. 3.

FIG. 5 is a partially schematic, cross-sectional illustration of a representative reactor vessel of the type shown in FIGS. 1 and 2.

FIG. 6 is a partially schematic, cross-sectional illustration of a representative reactor vessel configured in accordance with another embodiment of the present technology.

DETAILED DESCRIPTION Overview

Several examples of devices, systems and methods for efficiently producing hydrogen fuels and structural materials are described below. The efficiencies can result from using waste heat produced by a combustion engine to heat the reactor, and by returning at least some reaction products to the engine for combustion or other purposes. The overall process can result in clean-burning fuel and re-purposed carbon and/or other constituents for use in durable goods, including polymers and carbon composites. Although the following description provides many specific details of the following examples in a manner sufficient to enable a person skilled in the relevant art to practice, make and use them, several of the details and advantages described below may not be necessary to practice certain examples of the technology. Additionally, the technology may include other examples that are within the scope of the claims but are not described here in detail.

References throughout this specification to “one example,” “an example,” “one embodiment” or “an embodiment” mean that a particular feature, structure, process or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology.

Certain embodiments of the technology described below may take the form of computer-executable instructions, including routines executed by a programmable computer or controller. Those skilled in the relevant art will appreciate that the technology can be practiced on computer or controller systems other than those shown and described below. The technology can be embodied in a special-purpose computer, controller, or data processor that is specifically programmed, configured or constructed to perform one or more of the computer-executable instructions described below. Accordingly, the terms “computer” and “controller” as generally used herein refer to any data processor and can include internet appliances, hand-held devices, multi-processor systems, programmable consumer electronics, network computers, mini-computers, and the like. The technology can also be practiced in distributed environments where tasks or modules are performed by remote processing devices that are linked through a communications network. Aspects of the technology described below may be stored or distributed on computer-readable media, including magnetic or optically readable or removable computer discs as well as media distributed electronically over networks. In particular embodiments, data structures and transmissions of data particular to aspects of the technology are also encompassed within the scope of the present technology. The present technology encompasses both methods of programming computer-readable media to perform particular steps, as well as executing the steps.

A system in accordance with a particular embodiment of the technology includes an engine having a combustion region and an exhaust passage coupled to the engine to receive exhaust products from the combustion region. The exhaust passage can at least partially enclose a passage interior region. The system can further include a reactor having an external heat transfer surface positioned in the passage interior region, and a reaction zone positioned in a region enclosed by the external heat transfer surface. A hydrogen donor source can be coupled in fluid communication with the reaction zone of the reactor vessel via a donor passage, and a product passage can be coupled to the reaction zone to receive a reaction product from the reaction zone.

A system in accordance with another embodiment of the disclosed technology includes an engine having a combustion region, and an exhaust manifold coupled to the engine to receive exhaust products from the combustion region. The exhaust manifold can have a manifold external surface and a manifold internal surface at least partially enclosing an interior region, with insulation positioned around the external surface. The system can further include a reactor having a shell positioned in the interior region of the exhaust manifold, the shell having a shell external heat transfer surface, and a shell internal surface positioned around a reaction zone. A spiral heat transfer element is carried by the shell and projects into the passage interior region. A first wall is positioned annularly inwardly from the shell internal surface and is spaced radially apart from the shell internal surface to define a first annular passage. A second wall is positioned annularly inwardly from the first wall and spaced radially apart from the first wall to define a second annular passage positioned between the first and second walls, and a third passage positioned inwardly from the second wall. The second wall can include a porous medium that is transmissive to hydrogen but not transmissive to carbon compounds.

In still further embodiments, a representative system further includes an electrically-powered heater positioned in the second annular passage, and a galvanic circuit coupled across the second wall to pressurize the third passage. A hydrogen donor source is coupled to the first annular passage via a donor passage to direct a hydrogen donor to the reaction zone. A first product passage is coupled to the third passage to receive hydrogen, and a second product passage is coupled to the second annular passage to receive a carbon-bearing product. A liquid cooling system can be coupled to the engine to cool the engine, and can include a working fluid passage. A first heat exchanger can be coupled between the donor passage and the working fluid passage to transfer heat from the working fluid passage to the donor passage. The system can further include a second heat exchanger coupled between the donor passage and the exhaust manifold downstream of the reactor to transfer heat from the exhaust manifold to the donor passage. A third heat exchanger can be coupled between the donor passage and at least one of the first and second product passages to transfer heat from the at least one product passage to the donor passage. A turbine can be positioned downstream of the reactor and the spiral heat transfer element to extract energy from the flow that has passed around the reactor.

A method for operating an engine and a chemical reactor in accordance with a particular embodiment of the disclosed technology includes combusting a fuel in an engine to produce power and combustion products, directing the combustion products through an exhaust passage and around a reactor positioned within the exhaust passage, and transferring heat from the combustion products to a reaction zone within the reactor, via an external surface of the reactor. The method can further include directing a hydrogen donor into the reaction zone of the reactor, and dissociating the hydrogen donor into dissociation products in the reaction zone. The products can include a hydrogen-bearing constituent, and a non-hydrogen bearing constituent.

Representative Reactor Systems

FIGS. 1 and 2 illustrate representative reactor systems for producing hydrogen-based fuels and structural building blocks or architectural constructs in accordance with several embodiments of the technology. FIG. 1 illustrates the general arrangement of a reactor that uses waste heat from a combustion process. FIG. 2 illustrates further details of the reactor system, and illustrates mechanisms and arrangements by which the combustion engine and reactor can be coupled in a closed-loop fashion. FIGS. 3-6 illustrate further embodiments in which the reactor is positioned within an exhaust manifold.

FIG. 1 is a partially schematic illustration of a representative system 100 that includes a reactor 110. The reactor 110 further includes a reactor vessel 111 that encloses or partially encloses a reaction zone 112. In at least some instances, the reactor vessel 111 has one or more transmissive surfaces positioned to facilitate the chemical reaction taking place within the reaction zone 112. Suitable transmissive surfaces are disclosed in co-pending U.S. application Ser. No. 13/026,996, titled “REACTOR VESSELS WITH TRANSMISSIVE SURFACES FOR PRODUCING HYDROGEN-BASED FUELS AND STRUCTURAL ELEMENTS, AND ASSOCIATED SYSTEMS AND METHODS” (Attorney Docket No. 69545.8602US), filed on Feb. 14, 2011, and incorporated herein by reference. To the extent of the foregoing reference and/or any other references incorporated herein by reference conflict with the present disclosure, the present disclosure controls. In a representative example, the reactor vessel 111 receives a hydrogen donor provided by a donor source 130 to a donor entry port 113. For example, the hydrogen donor can include methane or another hydrocarbon. A donor distributor or manifold 115 within the reactor vessel 111 disperses or distributes the hydrogen donor into the reaction zone 112. The reactor vessel 111 also receives steam from a steam/water source 140 via a steam entry port 114. A steam distributor 116 in the reactor vessel 111 distributes the steam into the reaction zone 112. The reactor vessel 111 can further include a heater 123 that supplies heat to the reaction zone 112 to facilitate endothermic reactions. The power for the heater (e.g., electrical power) can be provided by a renewable energy source 165. The renewable energy source 165 can include a solar, wind, water and/or other suitable sustainable sources. The reactions performed at the reaction zone 112 can include dissociating methane or another hydrocarbon into hydrogen or a hydrogen compound, and carbon or a carbon compound. In other embodiments, the reactor 110 can dissociate other hydrogen donors, e.g. nitrogenous hydrogen donors. Representative reactions are further described in co-pending U.S. application Ser. No. 13/027,208 (referred to herein as the '208 Application) titled “CHEMICAL PROCESSES AND REACTORS FOR EFFICIENTLY PRODUCING HYDROGEN FUELS AND STRUCTURAL MATERIALS, AND ASSOCIATED SYSTEMS AND METHODS” (Attorney Docket No. 69545.8601US), filed on Feb. 14, 2011 and incorporated herein by reference. The products of the reaction exit the reactor vessel 111 via an exit port 117 and are collected at a reaction product collector 171 a.

The system 100 can further include a source 150 of radiant energy (e.g., waste heat) and/or additional reactants, which provides constituents to a passage 118 within the reactor vessel 111. For example, the heat/reactant source 150 can include a combustion chamber 151 that provides hot combustion/exhaust products 152 to the passage 118, as indicated by arrow A. The combustion products 152 and associated waste heat are produced by a process separate from the dissociation process (e.g., a power generation process). A combustion products collector 171 b collects combustion products exiting the reactor vessel 111 for further recycling and/or other uses. In a particular embodiment, the combustion products 152 can include hot carbon monoxide, water vapor, and/or other constituents. One or more transmissive surfaces 119 are positioned between the reaction zone 112 (which can be disposed annularly around the passage 118) and an interior region 120 of the passage 118. The transmissive surface 119 can accordingly allow radiant energy and/or a chemical constituent to pass radially outwardly from the passage 118 into the reaction zone 112, as indicated by arrows B. By delivering the radiant energy (e.g., heat) and/or chemical constituent(s) provided by the flow of combustion products 152, the system 100 can enhance the reaction taking place in the reaction zone 112, for example, by increasing the reaction zone temperature and/or pressure, and therefore the reaction rate, and/or the thermodynamic efficiency of the reaction. The foregoing process can accordingly recycle or reuse energy and/or constituents that would otherwise be wasted, in addition to facilitating the reaction at the reaction zone 112.

The composition and structure of the transmissive surface 119 can be selected to allow radiant energy to readily pass from the interior region 120 of the passage 118 to the reaction zone 112. Accordingly, the transmissive surface 119 can include glass, graphene, or a re-radiative component. Suitable re-radiative components are described further in co-pending U.S. application Ser. No. 13/027,015, titled “CHEMICAL REACTORS WITH RE-RADIATING SURFACES AND ASSOCIATED SYSTEMS AND METHODS” (Attorney Docket No. 69545.8603US), filed on Feb. 14, 2011 and incorporated herein by reference.

As noted above, the combustion products 152 can include steam and/or other constituents that may serve as reactants in the reaction zone 112. Accordingly, the transmissive surface 119 can be manufactured to selectively allow such constituents into the reaction zone 112, in addition to or in lieu of admitting radiant energy into the reaction zone 112. In a particular embodiment, the transmissive surface 119 can be formed from a carbon crystal structure, for example, a layered graphene structure. The carbon-based crystal structure can include spacings (e.g., between parallel layers oriented transverse to the flow direction A) that are deliberately selected to allow water molecules to pass through. At the same time, the spacings can be selected to prevent useful reaction products produced in the reaction zone 112 from passing out of the reaction zone. In particular embodiments, the transmissive surface 119 can be formed by using the same type of architectural constructs produced or facilitated by the reactor 110.

The system 100 can further include a controller 190 that receives input signals 191 (e.g., from sensors) and provides output signals 192 (e.g., control instructions) based at least in part on the inputs 191. Accordingly, the controller 190 can include suitable processor, memory and I/O capabilities. The controller 190 can receive signals corresponding to measured or sensed pressures, temperatures, flow rates, chemical concentrations and/or other suitable parameters, and can issue instructions controlling reactant delivery rates, pressures and temperatures, heater activation, valve settings and/or other suitable actively controllable parameters. An operator can provide additional inputs to modify, adjust and/or override the instructions carried out autonomously by the controller 190.

FIG. 2 is a partially schematic illustration of system 100 that includes a reactor 110 in combination with a radiant energy/reactant source 150 in accordance with another embodiment of the technology. In this embodiment, the radiant energy/reactant source 150 includes an engine 180, e.g., an internal combustion engine having a piston 182 that reciprocates within a cylinder 181. In other embodiments, the engine 180 can have other configurations, for example, an external combustion configuration. In an embodiment shown in FIG. 2, the engine 180 includes an intake port 184 a that is opened and closed by an intake valve 183 a to control air entering the cylinder 181 through an air filter 178. The air flow can be unthrottled in an embodiment shown in FIG. 2, and can be throttled in other embodiments. A fuel injector 185 directs fuel into the combustion zone 179 where it mixes with the air and ignites to produce the combustion products 152. Additional fuel can be introduced by an injection valve 189 a. The combustion products 152 exit the cylinder 181 via an exhaust port 184 b controlled by an exhaust valve 183 b. Further details of representative engines and ignition systems are disclosed in co-pending U.S. application Ser. No. 12/653,085 (Attorney Docket No. 69545.8304US) filed on Dec. 7, 2010, and incorporated herein by reference.

The engine 180 can include features specifically designed to integrate the operation of the engine with the operation of the reactor 110. For example, the engine 180 and the reactor 110 can share fuel from a common fuel source 130 which is described in further detail below. The fuel is provided to the fuel injector 185 via a regulator 186. The engine 180 can also receive end products from the reactor 110 via a first conduit or passage 177 a, and water (e.g., liquid or steam) from the reactor 110 via a second conduit or passage 177 b. Further aspects of these features are described in greater detail below, following a description of the other features of the overall system 100.

The system 100 shown in FIG. 2 also includes heat exchangers and separators configured to transfer heat and segregate reaction products in accordance with the disclosed technology. In a particular aspect of this embodiment, the system 100 includes a steam/water source 140 that provides steam to the reactor vessel 111 to facilitate product formation. Steam from the steam/water source 140 can be provided to the reactor 110 via at least two channels. The first channel includes a first water path 141 a that passes through a first heat exchanger 170 a and into the reactor vessel 111 via a first steam distributor 116 a. Products removed from the reactor vessel 111 pass through a reactor product exit port 117 and along a products path 161. The products path 161 passes through the first heat exchanger 170 a in a counter-flow or counter-current manner to cool the products and heat the steam entering the reactor vessel 111. The products continue to a reaction product separator 171 a that segregates useful end products (e.g., hydrogen and carbon or carbon compounds). At least some of the products are then directed back to the engine 180, and other products are then collected at a products collector 160 a. A first valve 176 a regulates the product flow. Water remaining in the products path 161 can be separated at the reaction product separator 171 a and returned to the steam/water source 140.

The second channel via which the steam/water source 140 provides steam to the reactor 110 includes a second water path 141 b that passes through a second heat exchanger 170 b. Water proceeding along the second water path 141 b enters the reactor 110 in the form of steam via a second stream distributor 116 b. This water is heated by combustion products that have exited the combustion zone 179 and passed through the transfer passage 118 (which can include a transmissive surface 119) along a combustion products path 154. The spent combustion products 152 are collected at a combustion products collector 160 b and can include nitrogen compounds, phosphates, re-used illuminant additives (e.g., sources of sodium, magnesium and/or potassium), and/or other compositions that may be recycled or used for other purposes (e.g., agricultural purposes). The illuminant additives can be added to the combustion products 152 (and/or the fuel used by the engine 180) upstream of the reactor 110 to increase the amount of radiant energy available for transmission into the reaction zone 112.

In addition to heating water along the second water path 141 b and cooling the combustion products along the combustion products path 154, the second heat exchanger 170 b can heat the hydrogen donor passing along a donor path 131 to a donor distributor 115 located within the reactor vessel 111. The donor vessel 130 houses a hydrogen donor, e.g., a hydrocarbon such as methane, or a nitrogenous donor such as ammonia. The donor vessel 130 can include one or more heaters 132 (shown as first heater 132 a and a second heater 132 b) to vaporize and/or pressurize the hydrogen donor within. A three-way valve 133 and a regulator 134 control the amount of fluid and/or vapor that exits the donor vessel 130 and passes along the donor path 131 through the second heat exchanger 170 b and into the reactor vessel 111. As discussed above, the hydrogen donor can also serve as a fuel for the engine 180, in at least some embodiments, and can be delivered to the engine 180 via a third conduit or passage 177 c.

In the reactor vessel 111, the combustion products 152 pass through the combustion products passage 118 while delivering radiant energy and/or reactants through the transmissive surface 119 into the reaction zone 112. After passing through the second heat exchanger 170 b, the combustion products 152 can enter a combustion products separator 171 b that separates water from the combustion products. The water returns to the steam/water source 140 and the remaining combustion products are collected at the combustion products collector 160 b. In a particular embodiment, the separator 171 b can include a centrifugal separator that is driven by the kinetic energy of the combustion product stream. If the kinetic energy of the combustion product stream is insufficient to separate the water by centrifugal force, a motor/generator 172 can add energy to the separator 171 b to provide the necessary centrifugal force. If the kinetic energy of the combustion product stream is greater than is necessary to separate water, the motor/generator 172 can produce energy, e.g., to be used by other components of the system 100. The controller 190 receives inputs from the various elements of the system 100 and controls flow rates, pressures, temperatures, and/or other parameters.

The controller 190 can also control the return of reactor products to the engine 180. For example, the controller can direct reaction products and/or recaptured water back to the engine 180 via a series of valves. In a particular embodiment, the controller 190 can direct the operation of the first valve 176 a which directs hydrogen and carbon monoxide obtained from the first separator 171 a to the engine 180 via the first conduit 177 a. These constituents can be burned in the combustion zone 179 to provide additional power from the engine 180. In some instances, it may be desirable to cool the combustion zone 179 and/or other elements of the engine 180 as shown. In such instances, the controller 190 can control a flow of water or steam to the engine 180 via second and third valves 176 b, 176 c and the corresponding second conduit 177 b.

In some instances, it may be desirable to balance the energy provided to the reactor 110 with energy extracted from the engine 180 used for other proposes. Accordingly, the system 100 can included a proportioning valve 187 in the combustion products stream that can direct some combustion products 152 to a power extraction device 188, for example, a turbo-alternator, turbocharger or a supercharger. When the power extraction device 188 includes a supercharger, it operates to compress air entering the engine cylinder 181 via the intake port 184 a. When the extraction device 188 includes a turbocharger, it can include an additional fuel injection valve 189 b that directs fuel into the mixture of combustion products for further combustion to produce additional power. This power can supplement the power provided by the engine 180, or it can be provided separately, e.g., via a separate electrical generator.

As is evident from the forgoing discussion, one feature of the system 100 is that it is specifically configured to conserve and reuse energy from the combustion products 152. Accordingly, the system 100 can include additional features that are designed to reduce energy losses from the combustion products 152. Such features can include insulation positioned around the cylinder 181, at the head of the piston 182, and/or at the ends of the valves 183 a, 183 b. Accordingly, the insulation prevents or at least restricts heat from being conveyed away from the engine 180 via any thermal channel other than the passage 118.

One feature of at least some of the foregoing embodiments is that the reactor system can include a reactor and an engine linked in an interdependent manner. In particular, the engine can provide waste heat that facilitates a dissociation process conducted at the reactor to produce a hydrogen-based fuel and a non-hydrogen based structural building block. The building block can include a molecule containing carbon, boron, nitrogen, silicon and/or sulfur, and can be used to form an architectural construct. Representative examples of architectural constructs, in addition to the polymers and composites described above are described in further detail in co-pending U.S. Application No. 13/027,214, titled “ARCHITECTURAL CONSTRUCT HAVING FOR EXAMPLE A PLURALITY OF ARCHITECTURAL CRYSTALS” (Attorney Docket No. 69545.8701) filed on Feb. 14, 2011 and incorporated herein by reference. An advantage of this arrangement is that it can provide a synergy between the engine and the reactor. For example, the energy inputs normally required by the reactor to conduct the dissociation processes described above can be reduced by virtue of the additional energy provided by the combustion product. The efficiency of the engine can be improved by adding clean-burning hydrogen to the combustion chamber, and/or by providing water (e.g., in steam or liquid form) for cooling the engine. Although both the steam and the hydrogen-based fuel are produced by the reactor, they can be delivered to the engine at different rates and/or can vary in accordance with different schedules and/or otherwise in different manners.

FIG. 3 is a partially schematic, cross-sectional illustration of a system 200 that includes a reactor 210 having a reactor vessel 211 positioned in an engine exhaust manifold or passage 220. The exhaust manifold 220 can be coupled to an engine 180 having a reciprocating internal combustion configuration generally similar to that described above with reference to FIG. 2. In other embodiments, the engine 180 can have other configurations, for example, a gas turbine configuration. In any of these embodiments, exhaust products from the engine 180 pass into the exhaust manifold 220 and around the reactor vessel 211 to provide heat to a reaction zone 212 located within the reactor vessel 211. Further details of a representative manner in which the reactor 210 is integrated with other features of the system 200 are described below with continued reference to FIG. 3. Further details of the reactor itself are described later with reference to FIGS. 4-6.

As shown in FIG. 3, the exhaust manifold 220 can have an interior region 221 through which exhaust gases from the exhaust port 184 b pass. The exhaust gases pass around the reactor vessel 211 as indicated by arrows E, and as they pass the reactor vessel 211, transfer heat into the reactor vessel 211. One or more heat transfer elements 213 can project into the interior region 221 of the exhaust manifold 220 to facilitate this heat transfer process. In particular embodiments, the reactor vessel 211 can also include an internal heater 214 that can, on an intermittent or continuous basis, supplement the heat provided to the reaction zone 212 by the exhaust gases passing through the manifold 220.

In a further aspect of an embodiment shown in FIG. 3, the externally projecting heat transfer elements 213 can be arranged to impart a spiral or radial flow component to the exhaust gases. Accordingly, when the exhaust gases pass downstream to a turbine 288 or other energy extraction device, the turbine 288 can extract the rotational kinetic energy. The turbine 288 can be coupled to an electric generator 277 via a shaft 287. The generator 277 can in turn provide the electrical energy to an energy storage medium 206 e.g. a battery, a bank of capacitors and/or another suitable medium. The electrical energy can be retrieved from the energy storage medium 206 to power the reactor heater 214 and/or other components of the system 200.

Exhaust gases exiting the turbine 288 can proceed downstream along a flow axis F past a heat exchanger 240 b which will be described later, and to an exhaust product separator 226. The exhaust product separator 226 can separate one or more constituents from the exhaust gas stream, and provide the constituents to an exhaust product collector 260 c. Separated exhaust products can then be directed to any of a number of suitable uses, for example, sulfur applications, fertilizer applications, and/or others, depending upon the composition of the exhaust gas products. Any remaining exhaust gas exits the exhaust manifold or passage 220 at an exit 225.

At least some portions, and in particular embodiments, all portions, of the exhaust manifold or passage 220 can include insulation 224 that prevents or at least restricts heat from escaping the manifold 220. Instead, this heat is directed to the reaction zone 212. This is unlike most conventional exhaust gas manifolds, which typically facilitate heat transfer to the external environment for purposes of cooling.

The system 200 can include one or more reactant vessels 230 (e.g. donor sources) that supply one or more reactants (e.g., hydrogen donors) to the reaction zone 212. The reactant is gaseous in several embodiments, and can be liquid and/or solid, or any suitable combination of phases in others. In particular embodiments, the donor includes a hydrogen donor, e.g., methane or another hydrocarbon. Suitable hydrocarbons include ethane, propane or butane, along with cetane and/or octane rated compounds. In still further embodiments, the reactant can include a lower grade constituent, e.g., off-grade cetane or octane rated hydrocarbons, or wet alcohol. In at least some embodiments, the donor substance can include compounds other than hydrocarbon fuels (e.g., carbohydrates, fats, alcohols, esters, cellulose and/or others). In yet further embodiments, the hydrogen donor can include hydrogen atoms in combination with constituents other than carbon. For example, nitrogenous compounds (e.g., ammonia and/or urea) can serve a similar hydrogen donor function. Examples of other suitable hydrogen donors are described in the '208 Application, previously incorporated herein by reference.

In yet further embodiments, the donor substance can donate constituents other than hydrogen. For example, the reactor 210 can dissociate oxygen from CO2 and/or another oxygen donor, or the reactor 210 can dissociate a halogen donor. In other embodiments, the donor can have other compositions and/or donate other constituents. In any of these embodiments, the donor is dissociated in the reaction zone 212 to produce two or more products. Accordingly, the system 200 can include multiple product collectors that collect the resulting products. In a particular embodiment shown in FIG. 3, the product collectors include a first product collector 260 a and a second product collector 260 b. In particular embodiments, as was discussed above with reference to FIGS. 1 and 2, the reactant vessel 230 can supply a hydrocarbon to the reaction zone 212. In the reaction zone 212, the hydrocarbon can be dissociated into hydrogen or a hydrogen-bearing compound (directed to the first product collector 260 a) and a carbon or carbon-bearing compound directed to the second product collector 260 b. The hydrogen can be stored and/or delivered to the combustion zone 179 of the engine 180 via a product delivery passage 262 and the fuel injector 185. The hydrogen alone or in combination with other constituents can accordingly form a hydrogen-characterized fuel. An optional water source 275 can deliver water to the combustion zone 179. The system 200 can include a number of heat exchangers (e.g., counter-current or counter-flow heat exchangers) and/or other features that increase the overall efficiency of the reactor 210, as will be described in further detail below.

As shown in FIG. 3, the reactant vessel 230 can perform multiple purposes. For example, in addition to supplying a reactant to the reaction zone 212, the reactant vessel 230 can supply fuel to the engine 180. In particular, in a manner generally similar to that described above with reference to FIG. 2, the reactant 230 can provide fuel (e.g. a hydrocarbon fuel) to the engine 180 via the fuel injector 185, under the control of the regulator 186. The reactant vessel 230 can include features for preheating the fuel/reactant/donor prior to delivering the reactant to the fuel injector 185 and/or the reaction zone 212. For example, the reactant vessel 230 can include an internal heater 232. In a particular aspect of this embodiment, the internal heater 232 can be a resistive heater, which receives electrical current from the energy storage medium 206 described above. The reactant vessel 230 can receive heat from other sources, in addition to or in lieu of the heater 232. Such sources can include a burner 233 that burns a portion of the reactant contained within the reactant vessel 230 (and/or another suitable fuel) and provides the resultant heat to the reactant vessel 230 via a heat pipe 234 or other suitable thermal transfer device. The heat provided to the reactant vessel 230 can vaporize and/or pressurize the reactant therein. As described above, suitable reactants can include methane or methanol, optionally with water, which can operate as an oxidant.

The reactant or donor (both terms are used herein to refer to the compound delivered to the reactor 210) exits the reactant vessel 230 via a reactant passage 231, which directs the reactant to the reaction zone 212 via one or more additional heat transfer arrangements that can further preheat the reactant before it arrives at the reaction zone 212. For example, the system 200 can include a first heat exchanger 240 a having a first heat exchange passage 241 a and a second heat exchange passage 242 a that are positioned in a counter-flow arrangement relative to each other. The reactant can pass through the first heat exchanger passage 241 a so as to receive heat from the second heat exchanger passage 242 a. The second heat exchanger passage 242 a can be coupled to an engine coolant circuit 276. The engine coolant circuit 276 can include antifreeze or another heat transfer working fluid that receives heat from the engine 180. In most conventional arrangements, this heat is rejected to the environment via a radiator. In the present embodiment, this heat is instead transferred to the reactant passing through the first heat exchanger passage 241 a. In a representative embodiment, the fluid in the second heat exchanger passage 242 a can have a temperature of up to about 105° C., and in other embodiments, the temperature can have other suitable values.

The reactant passage 231 can further be coupled to a second heat exchanger 240 b positioned at the exhaust manifold 220. The second heat exchanger 240 b can include a heat exchange passage 241 b that is in direct thermal communication with the exhaust flow passing through the exhaust manifold 220, to further preheat the reactant in the reactant passage 231. The temperature of the exhaust gas at this location (e.g., downstream of the turbine 288) can be up to about 600° C. in a representative embodiment.

The system 200 can further include a third heat exchanger 240 c that directs heat from products exiting the reactor 210 to the reactants entering the reactor 210. Accordingly, the third heat exchanger 240 c can include a first heat exchanger passage 241 c having a counter-flow arrangement relative to one or more second heat exchanger passages 242 c. In a particular embodiment shown in FIG. 2, the third heat exchanger 240 c includes two second heat exchanger passages 242 c, one coupled between the reactor 210 and the first product collector 260 a via a first product passage 261 a, and the other coupled between the reactor 210 and the second product collector 260 b via a second product passage 261 b. Accordingly, both products exiting the reactor 210 can preheat the reactant. In other embodiments (e.g., for which more than two products are separated) the third heat exchanger 240 c can include additional second heat exchanger passages 242 c.

In at least some instances, the system 200 can further include a supplemental reactant vessel 230 a coupled to the donor passage 231. Accordingly, the system 200 can supply an additional reactant (in addition to the reactant provided by the reactant vessel 230) into the reaction zone 212. Suitable constituents carried by the supplemental reactor 230 a can include but are not limited to methanol.

In a typical embodiment, the system 200 includes a vehicle 201 (e.g., a truck, a locomotive or another transportation medium) that carries the engine 180, the exhaust manifold 220 and the reactor 210. Accordingly, the system 200 includes one or more wheels 202, one of which is shown schematically in FIG. 3. The wheel or wheels 202 can be coupled to a regenerative brake 203 that converts kinetic energy from the wheel to electrical energy during a braking operation, and directs the electrical energy to the energy storage medium 206. The energy storage medium 206 can in turn direct the electrical energy to the reactant vessel heater 232, the reactor heater 214 and/or other electrically powered subsystems to increase the overall efficiency of the vehicle-based system 200. Further embodiments of regenerative brakes and other vehicle-based energy capture techniques are disclosed in U.S. application Ser. No. 13/584,786 (Attorney Docket No. 69545.8615US3) filed Feb. 11, 2013 and incorporated herein by reference.

When the vehicle 201 in not in use (or if the system 200 is fixed in place), the energy source 206 can be coupled to an electrical grid 204 via a power outlet 205 or other suitable arrangement. Accordingly, the energy source 206 can be recharged, e.g., during non-operational periods, so as to provide energy on an as-needed basis during operational periods. Power management tasks and other coordination tasks used to direct the operation of the reactor 210 and associated sub-systems can be controlled by a controller 290 that receives inputs 291 and provides appropriate outputs 292. The controller 290 can accordingly include one or more computer-readable media programmed with instruction that, when executed, carry out one or more of the tasks and operations described herein. Further details of the structure and operation of the reactor 210 are described below with reference to FIGS. 4 and 5.

FIG. 4 is a partially schematic, side cross-sectional illustration of an embodiment of the reactor 210 positioned within the exhaust manifold or passage 220. The manifold 220 can have a manifold internal surface 222 facing toward the reactor 210, and a manifold external surface 223 facing outwardly away from the reactor 210. As discussed above, the manifold 220 can be surrounded or at least partially surrounded with insulation 224 (e.g., a ceramic or other suitable material) that prevents or at least restricts heat from escaping via the manifold external surface 223. Instead, such heat is available for transfer by convection, conduction, and/or radiation to the manifold interior region 221 and the reactor 210.

The reactor 210 can include a shell 215 having a shell internal surface 216 a and a shell external surface 216 b. The external surface 216 b can include a highly thermally conductive, heat-resistant and oxidation-resistant material (e.g. a super alloy that includes nickel and/or cobalt, or another high temperature furnace alloy) to facilitate transferring heat from the exhaust gas to the reaction zone 212 within the reactor 210. Unlike the arrangement described above with reference to FIG. 2, the shell 215 can prevent constituent transfers into the reactor 220 from the adjacent exhaust flow, while permitting heat transfer from the exhaust flow. As discussed above, the reactor 210 can further include one or more heat transfer elements 213 that project from the shell 215 into the interior region 221 of the manifold 220 to extract additional thermal energy from the exhaust gas and conduct that energy to the reaction zone 212 via the shell 215. In a particular embodiment, the heat transfer element 213 can have a generally spiral shape that, in addition to extracting heat from the passing exhaust flow, imparts a rotational motion to the exhaust flow, which can be extracted by the turbine 288 described above with reference to FIG. 3. In one embodiment, the heat transfer element 213 can include a single screw-shaped annular element. In other embodiments, the heat transfer element 213 can have multiple components, e.g., multiple vanes, fins, or other surfaces that are at least partially inclined relative to the axial gas flow direction indicated by arrows E. Accordingly, any of these arrangements can generate the spiral flow pattern indicated by arrows S. The heat transfer elements can generally have a high surface area-to-volume ratio so as to increase the efficiency with which they collect and transmit heat.

The reactor 210 can have one or more annularly-positioned flow passages, defined by one or more corresponding walls. For example, the reactor vessel 211 can include a first wall 251 (e.g., in the form of a capped tube) positioned inwardly from the shell 215 to define, at least in part, a first passage 253 a. The vessel 211 can further include a second wall 252 (e.g., in the form of a capped tube) positioned radially inwardly from the first wall 251. Accordingly, the second wall 252 can define, at least in part, a second passage 253 b positioned between the first wall 251 and the second wall 252, and a third passage 253 c positioned inwardly from the second wall 252. The first wall 251 can be generally solid and thermally insulated or non-transmissive, so as to restrict or prevent the loss of heat generated by the reaction heater 214. Accordingly, a reactant flow provided by the reactant passage 231 can receive heat from the shell 215 as it travels axially along the annular first passage 253 a, as indicated by arrows D. The first wall 251 can include openings or perforations 250 toward a distal end DE of the first passage 253 a, allowing the reactant to pass inwardly into the second passage 253 b. The reactant then travels back in a proximal direction through the second passage 253 b toward a proximal end PE of the reactor 210.

As the reactant receives heat in both the first and second passages 253 a, 253 b, it begins to oxidize, partially oxidize, reform, and/or dissociate in a non-combustion, endothermic reaction process, forming one or more first products and one or more second products. These processes can be conducted in accordance with the parameters described in the '208 Application previously incorporated herein by reference. Representative reactions include:

Heat+CH4+H2O→CO+3H2  Equation 1

Heat+CH4→C+2H2  Equation 2

Heat+CH3OH→CO+2H2  Equation 3

Heat+CH3OH+H2O→CO2+3H2  Equation 4

Heat+CH3IH+“C”+H2O→2CO+3H2  Equation 5

Heat+CxHy+xH2O→xCO+(0.5y+x)H2  Equation 6

Heat+2NH3→N2+3H2  Equation 7

Heat+CO(NH2)2→CO+2H2+N2  Equation 8

Heat+CO(NH2)2+H2O→CO2+3H2+N2  Equation 9

CH4+0.5O2→CO+3H2+Heat  Equation 10

HxCy+y/2O2→yCO+x/2H2  Equation 11

HxCy=yH2O→yCO=(y+x/2)H2  Equation 12

In at least some cases, various carbon donors (identified as “C” in Equation 5) can contribute further carbon to the foregoing reactions. Suitable carbon donors can include coal, grain dust, food and/or farm wastes. In addition to or in lieu of such sources, optional surfactants can be added to improve emulsion stability, including surfactants that may also contribute carbon in the endothermic reaction. In at least some embodiments (e.g., as indicated by Equations 10-12), exothermic and/or partial oxidation reactions can contribute heat to the foregoing endothermic reactions.

In particular embodiments, the first products include hydrogen or hydrogen compounds, and the second products include carbon or carbon compounds. The second wall 252 can be constructed to separate these two products and direct each to a respective one of the first product collector 260 a or the second product collector 260 b described above with reference to FIG. 3. In a particular embodiment, the second wall 252 can include a porous medium 254 having porous surfaces 255 and being selectively transmissive to hydrogen or selected hydrogen compounds, but is not transmissive to carbon or carbon compounds. Accordingly, hydrogen can pass into the third passage 253 c as indicated by arrows H, and carbon or carbon compounds can remain in the second passage 253 b, as indicated by arrows C. The hydrogen is then collected at the first product passage 261 a, and the carbon or carbon compounds are collected at the second product passage 261 b.

In one embodiment, the second wall 252 can be manufactured by winding selected filaments on a temporary forming mandrel sized to match or approximately match the inner diameter of this tube-shaped element. The fibers can be wound in a pattern that is selected or optimized for reinforcing a pressure-containing vessel. Filaments suitable for such purposes include polyacrylonitrile (PAN) including co-polymers and solutions with other compounds, pitch fiber, along with carbon fiber, silicon carbide and/or other suitable filament selections. The resulting matrix can then be heat treated and/or subjected to other furnace operations to convert the PAN to carbon. Additional carbon can be added to (e.g., deposited on) the matrix by one or more steps similar to the reaction identified above in Equation 2. The resulting structure can accordingly include a porous network that favors hydrogen (e.g., separates hydrogen) from feedstocks such as natural gas liquids and other reactants listed in Equations 1-9, as well as from other products listed in Equations 1-9 above.

In another embodiment, the tube forming the second wall 252 can be formed by compacting graphene, carbon, and/or other powders with one or more suitable organic polymers and/or binders, followed by heat treating to convert the organics and/or binders and densification to the degree desired for separation of hydrogen and/or carbon monoxide from other gases such as the reactants of Equations 1-9. In particular, densifiying the matrix can include producing nanomaterials such as nanotubes, fibers, and whiskers by the technologies disclosed in U.S. Application Publication No. 2009/0186214, U.S. Pat. No. 8,158,217 and/or U.S. Pat. No. 8,168,291. Accordingly, the products formed at the reactor 210 can be used to form new structures for additional reactors. In particular, the carbon extracted from a hydrocarbon in one process can be used to form the porous medium that is used to separate additional carbon and hydrogen in a subsequent process.

In still further embodiments, the tube forming the second wall 252 can be repaired or repurposed after use in the reactor 210. For example, the initial use of the tube as a component of an exhaust manifold provides a highly purified, sterilized, and refined micro-porous electrode or filter matrix. After such use, the tube can have deposited on it a carbon fuzz so that the tube can function as a high value electrode for electro-dialysis or as a filter for fluids such as air, water, beer, whiskey, wine or pharmaceutical products.

The temperature of the reaction zone 212 may vary depending upon the operational state of the engine 180 (FIG. 3). For example, during cold engine startup, the exhaust gases will have a relatively low temperature e.g., 120° C. As the engine warms up, the exhaust gas temperature will increase e.g., to 300° C. for idle, coasting or lightly loaded operation. At maximum load conditions, the exhaust gas temperature can increase to 700° C. In any of these embodiments, the reactor heater 214 can supplement the energy provided to the reaction zone 212. The heater 214 can be an electrical resistance heater or induction heater that, under the control of the controller 290 (FIG. 3) provides the requisite amount of heat. In some embodiments, the heater 214 is activated only during engine operational phases that result in relatively low exhaust gas temperatures. In other embodiments, the heater 214 is active at all times, but provides more heat during some operational phases than others. For example, a typical temperature for hydrogen dissociation is at least 650° C., and in several embodiments, it is desirable to conduct the reaction at higher temperatures (e.g., at least 700° C. and in particular, from about 750° C. to about 1600° C.). Such elevated temperatures can produce product pressures high enough to support injecting the products (e.g., hydrogen) into a high compression ratio engine. In at least some instances, the heat transferred to the reactant via the engine coolant, the exhaust downstream of the turbine 288, and the exhaust upstream of the turbine 288 may be insufficient to elevate the reaction zone 212 to these temperatures. In such instances, the reactor heater 214 may operate at all times when the reactor 210 operates, but, as described above, its energy output can vary depending on the engine operational state and by extension reaction zone temperature. Temperature sensors, pressure sensors, and/or other feedback devices are used to determine the operational states and/or parameters of the system 200 to provide suitable information to the controller 290.

In another aspect of an embodiment shown in FIG. 4, the reaction vessel 211 can include one or more galvanic circuits 217, each of which can include one or more cathodes 218 a and one or more anodes 218 b. The galvanic circuit 217 can be coupled to the energy storage medium 206 (FIG. 3) to provide a voltage across the second wall 252. When activated, the galvanic circuit can pressurize the hydrogen collected in the third passage 253 c, which can in turn facilitate the dissociation process conducted in the reaction zone 212 by reducing the hydrogen partial pressure in the reaction 212. In addition, hydrogen at elevated pressures within the third passage 253 c can be used to facilitate high-pressure fuel injection at the injector 185 (FIG. 3). Representative pressures include 200 Bar (gage) or higher.

Galvanic separation can facilitate the foregoing hydrogen separation and pressurization processes, e.g., by proton conduction. Composites and ceramics such as perovskite (SrCeO3) oxide can provide suitable media for such processes, and can be used in addition to the porous medium described above. In particular, gas volumes at elevated temperatures, that include hydrogen, can be separated at increased rates by doped perovskite-type oxides. Such enhanced proton conductivity is provided with membranes such as doped SrCeO3, CaZrO3, BaCeO3 and/or SrZrO3. Suitable dopants include yttrium, ytterbium, europium, samarium, neodymium, and gadolinium.

Hydrogen separation by such oxide ceramics can be further enhanced by an increased pressure gradient and/or via a DC bias. In embodiments that apply a DC bias or galvanic drive in the hydrogen separation process, the hydrogen can permeate from a lower hydrogen pressure on one side of the membrane to a higher hydrogen partial pressure on the other side of the membrane, or vice versa. By contrast, in a non-galvanic hydrogen separation process in which a pressure difference exists across a separation membrane, transport is only from the high hydrogen partial pressure side to the low hydrogen partial pressure side of the membrane.

Catalysts may be utilized at a reaction surface to influence surface exchange reactions such as various steps or the processes of Equations 1, 2, and/or 7 above, and the hydrogen permeation can be enhanced by coating the membrane with a surface catalyst to reduce the activation energy for the surface exchange reactions. In particular embodiments, the selected anode material is also a favorable catalyst. Representative anodes for galvanic hydrogen pumps include porous films of Ni, Ag, Pt, and Ni/BCY porous layer. In such hydrogen pumping processes, the gas mixture in the anode and cathode zones compartments can include steam or be humidified with water vapor to improve the proton conductivity of the electrolyte and suppress its electronic conductivity.

The hydrogen separation rate increases as the applied current is increased in accordance with Faraday's law. Depending upon factors such as reactant pressure and temperature, dopant selection, membrane thickness, and humidity, the applied galvanic voltage gradients can have values in a representative range of from about 0.2 VDC to about 20 VDC, which are sufficient to produce substantially higher pressure hydrogen. Such net galvanic voltage gradients may be produced by much higher voltage AC or DC electricity delivered to the reactor heater 214.

Thus various mixtures of reactants and products such as H2 along with C0, CO2, H2O, and/or N2 in the anode zone can be separated to provide pressurized H2 at the cathode zone. Such hydrogen pressurization driven by an applied external voltage can move hydrogen from a suitably pressurized gas mixture including reactants and products to higher pressure for delivery for denser storage and injection purposes. In particular embodiments, reactants are delivered to the anode 218 b at 61 Bar (900PSI) and are reacted to produce hydrogen that is removed to improve the reaction yield and delivered by galvanic separation at voltage gradients of 0.2 to 20VD to the cathode 218 a, at 122 Bar (1800PSI).

As shown in FIG. 4, embodiments of the present technology include a coaxial flow circuit that heats the reactants in the first passage 253 a via exhaust gases, and then directs the gases into the second passage 253 b wherein the foregoing galvanic process facilitates hydrogen separation and pressurization. Accordingly, the exhaust gases can provide an initial quantity of heat alone or in combination with the heat received from heat transfer processes described above with reference to FIG. 4. Additional heat, e.g., obtained from a regenerative braking process, can be provided at higher and adaptively controlled temperatures to produce hydrogen at the desired rate and/or pressure needed to optimize or at least improve operation of the engine 180 (FIG. 3).

Reactants delivered to the anode within the tube bore at 61 Bar (900PSI) can be reacted to produce hydrogen that is removed to improve the reaction yield and delivered by galvanic separation at voltage gradients of 0.2 to 20VD to the cathode at the outside zone of the separator tube at 122 Bar (1800PSI). The pressurized hydrogen can be directly injected into the engine 180 (FIG. 3).

FIG. 5 is an end cross-sectional illustration of a portion of the system 200 described above with reference to FIGS. 3 and 4. FIG. 5 illustrates the manifold 220 attached to the engine 180 with an arrangement that, in addition to or in lieu of the insulation 224 reduces or prevents heat loss, so as to preserve the available heat for heating the reactor 210. For example, the system 200 can include a thermally insulating gasket 274 between the manifold 220 and the engine 180. The manifold 220 can be fastened to the engine 180 with thermally isolating or insulating elements. Such elements can include a thermally non-conductive bolt 269 and nut 271, thermally insulating washers 272, a compression disk spring 270, and/or a fastener isolator tube 273, all of which reduce thermal losses. As a result, the efficiency with which the reaction carried out in the reactor 210 is conducted can be improved relative to the systems that do not include such insulating features.

FIG. 6 is a partially schematic, cross-sectional illustration of a reactor 610 configured in accordance with another embodiment of the present technology, and disposed in the exhaust manifold 220 in a manner generally similar to that described above with reference to FIGS. 3-5. Accordingly, aspects of the reactor 610 shown in FIG. 6 that are similar or generally similar to corresponding aspects of the reactor 220 described above are not described in detail below.

In a particular aspect of an embodiment shown in FIG. 6, the reactor 610 includes a reactor vessel 611 that encloses an inwardly disposed, first wall 651 having a construction generally similar to the construction of the second wall 252 described above with reference to FIG. 4. Accordingly, the first wall 651 can include a hydrogen-selective porous medium. The first wall 651 can enclose a first passage 653 a through which the hydrogen donor passes, as indicated by arrows D. Heat is provided to the first passage 653 a via heat transfer from the exhaust gas flow (indicated by arrows E), supplemented in at least some operational phases with heat provided by the reactor heater 214. Accordingly, the first passage 653 a forms a reaction zone 612. As the carbon donor dissociates in the reaction zone 612, the hydrogen passes outwardly through the first wall 651 into a second passage 653 b as indicated by arrows H. The hydrogen passes out of the second passage 653 b via a first product passage 261 a, and the remaining carbon and/or carbon compounds pass outwardly from the reactor 610 via a second product passage 261 b, as indicated by arrows C. The galvanic circuit 217 can include one or more cathodes 218 a positioned in the second flow passage 653 b, and one or more anodes 218 b positioned in the first passage 253 a. Accordingly, the pressure in the second passage 653 b can be higher than the pressure in the first passage 653 a, which can place a compressive force on the first wall 651. As a result, the first wall 651 can be sized to withstand a radially compressive force, rather than a radially expansive force, which can reduce the thickness of the first wall 651 and/or increase the material options available for the first wall 651.

In addition to producing hydrogen for fuel or other purposes, the reactor 210 can produce carbon and/or carbon compounds, which can have still further uses. For example representative carbon-based products from the reactor 210 include carbon, silicon carbide, halogenated hydrocarbons, graphite, and graphene. These products can be further processed, e.g., to form carbon films, ceramics, semiconductor devices, polymers and/or other structures. For example, the products can include carbon pipes, sheets, the second wall described above, and/or other suitable structures. Accordingly, the products of the reaction conducted in the reactor 210 can be architectural constructs or structural building blocks that can be used as is or after further processing. Other suitable products are described in the '208 Application.

One feature of several of the embodiments described with reference to FIGS. 3-6 is that the systems can include insulated exhaust manifolds, in combination with reactor surfaces that are highly thermally conductive. This combination can result in low thermal mass, low thermal inertia, and high thermal shock resistance. As a result, the efficiency of the dissociation reaction carried out at the reactor can be significantly greater than for systems that do not include these features.

Other features of the foregoing embodiments include the ability to use significantly less expensive fuels, including methane produced from sewage, garbage, farm wastes, and/or forest slash, in addition to or in lieu of natural gas, with considerably higher efficiencies than are available with conventional diesel engines. In addition to being less expensive, such fuels are generally more easily and quickly renewed than are conventional fuels. Engines converted to use such fuels can last longer than conventional engines, produce higher peak power, and/or reduce objectionable emissions. One feature that contributes to reduced emissions is not throttling the engine 180. The efficiency with which such fuels are generated is increased by using engine heat that is otherwise wasted. Excess energy can be readily stored at the energy storage medium 206.

Still further features include capturing heat and energy from the engine exhaust system, which has lower pressures and kinetic energy levels than other portions of the engine, and is therefore safer. In addition, the insulation provided around the exhaust manifold can provide a containment shell that further increases engine safety. Still further, the system is configured to absorb very large amounts of braking energy, via regenerative brakes, without generating unsafe heat levels.

In particular embodiments, the arrangement selected for a given reactor can depend on the power of the engine 180 to which it is coupled. For example, the arrangement shown in FIG. 2 may be more suitable for larger engines (e.g., greater than 700 HP) for which high fuel use rates correspond to high radiant energy rates. The reactor shown in FIG. 2 is configured at least in part to make use of these elevated radiant energy levels. By contrast, the arrangement shown in FIGS. 3-6 may be more suitable for smaller engines (e.g., less than 700 HP) which do not generate as much radiant energy and which tend to be cheaper. In particular, many of the components used in the arrangements shown in FIGS. 3-6 can be formed from 310 stainless steel or other more reasonably priced materials.

From the foregoing, it will appreciated that specific embodiments of the technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. For example, certain embodiments of the processes described above were described in the context of methane. In other embodiments, other hydrocarbon fuels or non-carbon-containing hydrogen donors can undergo similar processes to form hydrogen-based fuels and architectural constructs. The waste heat provided by the engine can be supplemented by other waste heat sources, e.g., waste heat from regenerative braking.

Certain aspects of the technology described in the context of particular embodiments may be combined or eliminated in other embodiments. For example, in some embodiments, selected heat exchangers can be eliminated or combined. Further while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the present disclosure. Accordingly, the present disclosure and associated technology can encompass other embodiments not expressly shown or described herein. 

I claim:
 1. A chemical reactor system, comprising: an engine having a combustion region; an exhaust passage coupled to the engine to receive exhaust products from the combustion region, the exhaust passage at least partially enclosing a passage interior region; a reactor having an external heat transfer surface positioned in the passage interior region, the reactor further having a reaction zone positioned in a region enclosed by the external heat transfer surface; a hydrogen donor source; a donor passage coupled in fluid communication with the hydrogen donor source and the reaction zone of the reactor vessel; and a product passage coupled to the reaction zone to receive a reaction product from the reaction zone.
 2. The system of claim 1 wherein the product passage is a first product passage positioned to receive hydrogen from the reaction zone, and wherein the system further comprises a second product passage positioned to receive a carbon-bearing product from the reaction zone.
 3. The system of claim 2, further comprising a porous medium positioned between the first product passage and the second product passage, the porous medium being selective for hydrogen.
 4. The system of claim 2, further comprising a galvanic circuit coupled between the first and second product passages to pressurize hydrogen in the first product passage.
 5. The system of claim 1, further comprising at least one heat transfer element carried by the external heat transfer surface and projecting into the passage interior region.
 6. The system of claim 5 wherein the exhaust passage is elongated along a flow axis, and wherein the at least one heat transfer element is arranged in an at least partially spiral manner relative to the flow axis.
 7. The system of claim 6, further comprising a turbine coupled to the exhaust passage downstream of the reactor.
 8. The system of claim 1 wherein the reaction zone is bounded in part by a porous surface, the porous surface being transmissive to hydrogen and not transmissive to carbon compounds.
 9. The system of claim 1, further comprising an electrically powered heater positioned in thermal communication with the reaction zone.
 10. The system of claim 9 wherein the electrically powered heater includes at least one of an inductive heater and a resistive heater.
 11. The system of claim 1 wherein the electrically powered heater is positioned within the reaction zone.
 12. The system of claim 1 wherein the engine and reactor are carried by a vehicle, and wherein the vehicle includes a regenerative brake coupled to an electricity storage medium.
 13. The system of claim 1, further comprising a heat exchanger coupled in thermal communication with the donor passage to transfer heat to a flow volume in the donor passage.
 14. The system of claim 13, further comprising a liquid cooling system coupled to the engine to cool the engine, the liquid cooling system including working fluid passage, and wherein the heat exchanger includes: a first heat exchanger passage coupled to the donor passage; and a second heat exchanger passage coupled to the working fluid passage and in thermal communication with the first heat exchanger passage at the heat exchanger.
 15. The system of claim 13 wherein the heat exchanger includes: a first heat exchanger passage coupled to the donor passage; and a second heat exchanger passage coupled to the products passage and in thermal communication with the first heat exchanger passage at the heat exchanger.
 16. The system of claim 13 wherein the heat exchanger includes: a heat exchanger passage coupled to the products passage and in thermal communication with the exhaust passage, downstream of the reactor.
 17. The system of claim 1, further comprising insulation positioned around the exhaust passage.
 18. The system of claim 1 wherein the reactor includes: a first annular passage positioned inwardly from the heat transfer surface; a second annular passage positioned inwardly from the first annular passage; and a third passage positioned inwardly from the second annular passage.
 19. The system of claim 18 wherein: the product passage is a first product passage positioned to receive hydrogen from the reaction zone, and wherein the system further comprises a second product passage positioned to receive a carbon-bearing product from the reaction zone; the first annular passage is coupled to the donor passage; the second annular passage is coupled to the second product passage; and the third passage is coupled to the first product passage.
 20. The system of claim 1, further comprising a fuel passage coupled between the product passage and the combustion region of the engine to direct the reaction product to the combustion region.
 21. A chemical reactor system, comprising: an engine having a combustion region; an exhaust manifold coupled to the engine to receive exhaust products from the combustion region, the exhaust manifold having a manifold external surface the exhaust manifold further having a manifold internal surface at least partially enclosing an interior region; insulation positioned around the external surface of the exhaust manifold; a reactor, comprising a shell positioned in the interior region of the exhaust manifold, the shell having a shell external heat transfer surface, the shell further having a shell internal surface positioned around a reaction zone, and; a spiral heat transfer element carried by the shell and projecting into the passage interior region; a first wall positioned annularly inwardly from the shell internal surface and spaced radially apart from the shell internal surface to define a first annular passage; a second wall positioned annularly inwardly from the first wall and spaced radially apart from the first wall to define a second annular passage positioned between the first and second walls, and a third passage positioned inwardly from the second wall, the second wall including a porous medium transmissive to hydrogen but not transmissive to carbon compounds; an electrically-powered heater positioned in the second annular passage; and a galvanic circuit coupled across the second wall to pressurize the third passage; a hydrogen donor source; a donor passage coupled between the hydrogen donor source and the first annular passage to direct a hydrogen donor to the reaction zone a first product passage coupled to the third passage to receive hydrogen a second product passage coupled to the second annular passage to receive a carbon-bearing product; a liquid cooling system coupled to the engine to cool the engine, the liquid cooling system including working fluid passage; a first heat exchanger coupled between the donor passage and the working fluid passage to transfer heat from the working fluid passage to the donor passage; a second heat exchanger coupled between the donor passage and the exhaust manifold downstream of the reactor to transfer heat from the exhaust manifold to the donor passage; a third heat exchanger coupled between the donor passage and at least one of the first and second product passages to transfer heat from the at least one product passage to the donor passage; and a turbine positioned downstream of the reactor and the spiral heat transfer element.
 22. A method for operating an engine and a chemical reactor, comprising: combusting a fuel in an engine to produce power and combustion products; directing the combustion products through an exhaust passage and around a reactor positioned within the exhaust passage; transferring heat from the combustion products to a reaction zone within the reactor, via an external surface of the reactor; directing a hydrogen donor into the reaction zone of the reactor; dissociating the hydrogen donor into dissociation products in the reaction zone; from the dissociation products, providing: (a) a hydrogen-bearing constituent; and (b) a non-hydrogen bearing constituent.
 23. The method of claim of claim 22 wherein transferring heat from the combustion zone to the reaction zone includes: transferring heat from the combustion products to at least one heat transfer element carried by the reactor and projecting into the passage interior region; and transferring heat from the at least one heat transfer element to the reaction zone.
 24. The method of claim 23 wherein the at least one heat transfer element has a spiral shape, and wherein transferring heat from the combustion products to at least one heat transfer element includes directing the exhaust products along the heat transfer element to impart a rotational flow component to the exhaust products.
 25. The method of claim 24, further comprising extracting kinetic energy from the exhaust products by directing the exhaust products through a turbine downstream of the at least one heat transfer element.
 26. The method of claim 22, further comprising providing heat to the reaction zone via an electrically-powered heater.
 27. The method of claim 22, wherein the engine and reactor are carried by a vehicle, and wherein the method further comprises: braking the vehicle with a regenerative brake; and directing electrical power obtained from the regenerative brake to the reactor.
 28. The method of claim 22, further comprising: cooling the engine with a coolant fluid; and directing heat from the coolant fluid to the hydrogen donor before the hydrogen donor enters the reaction zone.
 29. The method of claim 22, further comprising directing heat from the dissociation products to the hydrogen donor before the hydrogen donor enters the reaction zone.
 30. The method of claim 22, further comprising directing heat from the combustion products to the hydrogen donor before the hydrogen donor enters the reaction zone.
 31. The system of claim 22, further comprising at least restricting heat loss from the exhaust passage with insulation positioned around the exhaust passage.
 32. The method of claim 22 wherein the reactor includes: an outwardly facing heat transfer surface positioned in the flow of exhaust products; a first annular passage positioned inwardly from the heat transfer surface; a second annular passage positioned inwardly from the first annular passage; and a third passage positioned inwardly from the second annular passage; and wherein the method further comprises: directing the hydrogen donor axially through the first passage in a first direction to heat the hydrogen donor; directing the hydrogen donor axially through the second passage in a second direction opposite the first direction; and directing dissociated hydrogen into the third passage.
 33. The method of claim 22 wherein directing the dissociated hydrogen includes directing the dissociated hydrogen through a porous medium separating the second and third passages.
 34. The method of claim 22, further comprising combusting at least a portion of the hydrogen-bearing constituent in the combustion chamber.
 35. The method of claim 22, further comprising separating hydrogen from carbon-bearing constituents of the dissociation products by exposing the dissociation products to a porous medium that is transmissive to hydrogen but not transmissive to carbon compounds.
 36. The method of claim 35 wherein the porous medium is a first porous medium, and wherein the method further comprises forming a second porous medium from the carbon-bearing constituents.
 37. The method of claim 35, further comprising: removing the porous medium from the reactor; and using the porous medium to purify at least one of air or water.
 38. The method of claim 35, further comprising pressurizing the hydrogen by applying a galvanic current across the porous medium. 